chore: remove skill distribution layer

[pentaxis93]

Summary

agentd vendors and distributes methodology skills via loadout. In the three-layer architecture (daemon → runtime → methodology), skill distribution is not agentd's concern. Operators acquire methodology plugins independently. The runtime (runa) reads them from a path. agentd provides the container, identity, credentials, network, and context — not skills.

Remove all skill distribution artifacts.

Scope

Remove:

• skills/ — vendored skill files
• skills.manifest.toml — vendor manifest
• scripts/skills_sync.sh — vendor sync script
• scripts/skills_verify.sh — vendor verification script
• .loadout/ — loadout pilot configuration
• tests/loadout_pilot_smoke.sh — loadout smoke test
• tests/gitignore_skill_targets_smoke.sh — gitignore smoke test
• docs/personal-skill-overlay.md — loadout overlay documentation
• docs/skills-loadout-pilot-spec.md — loadout pilot spec
• Makefile — only contains skill targets

Update:

• README.md — remove "Developer Tooling: Skills" section and loadout references
• AGENTS.md — remove skill management references; keep development discipline (ground, BDD, coherence on landing) but note these come from the methodology plugin, not from agentd
• .gitignore — remove /.agents/skills, /.claude/skills, /.opencode/skills entries. Keep /target.
• .github/workflows/skills.yml — remove loadout and skill verification steps. Keep cargo test --workspace, build, clippy, fmt. Rename to ci.yml.

Acceptance Criteria

• No files or directories related to skill distribution remain in the repo
• cargo build --workspace succeeds
• cargo test --workspace succeeds
• CI workflow runs build, test, clippy, fmt — no loadout or skill steps
• README describes agentd without referencing skills, loadout, or methodology distribution
• AGENTS.md references methodology skills as externally provided, not vendored
• .github/workflows/ contains a clean CI workflow with no skill verification
• git status after checkout shows no untracked skill directories

Dependencies

None.